diff options
authorHeiko Stuebner <heiko@sntech.de>2018-11-09 10:48:57 +0100
committerLee Jones <lee.jones@linaro.org>2018-11-27 12:10:51 +0000
commite4c8ae3e3d6d473bfbfbb5db234792b9f8ddab3b (patch)
parent651022382c7f8da46cb4872a545ee1da6d097d2a (diff)
backlight: pwm_bl: Re-add driver internal enabled tracking
Commit e6bcca0890b9 ("backlight: pwm_bl: Switch to using "atomic" PWM API") removed the driver internal enabled tracking in favor of simply checking the pwm state. This can lead to issues as all of gpio-, regulator- and pwm-state are used to determine the initial state and the bootloader or kernel can leave them in an inconsistent state at boot. In my case on rk3399-kevin, the pwm backlight is build as module and the kernel disables the supply regulator as unused while keeping the pwm running thus pwm_bl calling pwm_backlight_power_off() during probe and creating an unmatched regulator-disable call, as it never got enabled from the pwm-bl before. To prevent these consistency issues, reintroduce the driver-internal tracking of the enabled state. Fixes: e6bcca0890b9 ("backlight: pwm_bl: Switch to using "atomic" PWM API") Signed-off-by: Heiko Stuebner <heiko@sntech.de> Acked-by: Thierry Reding <thierry.reding@gmail.com> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 678b27063198..bcd08b41765d 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -30,6 +30,7 @@ struct pwm_bl_data {
struct device *dev;
unsigned int lth_brightness;
unsigned int *levels;
+ bool enabled;
struct regulator *power_supply;
struct gpio_desc *enable_gpio;
unsigned int scale;
@@ -50,7 +51,7 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb)
int err;
pwm_get_state(pb->pwm, &state);
- if (state.enabled)
+ if (pb->enabled)
err = regulator_enable(pb->power_supply);
@@ -65,6 +66,8 @@ static void pwm_backlight_power_on(struct pwm_bl_data *pb)
if (pb->enable_gpio)
gpiod_set_value_cansleep(pb->enable_gpio, 1);
+ pb->enabled = true;
static void pwm_backlight_power_off(struct pwm_bl_data *pb)
@@ -72,7 +75,7 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)
struct pwm_state state;
pwm_get_state(pb->pwm, &state);
- if (!state.enabled)
+ if (!pb->enabled)
if (pb->enable_gpio)
@@ -86,6 +89,7 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)
pwm_apply_state(pb->pwm, &state);
+ pb->enabled = false;
static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)
@@ -483,6 +487,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
pb->check_fb = data->check_fb;
pb->exit = data->exit;
pb->dev = &pdev->dev;
+ pb->enabled = false;
pb->post_pwm_on_delay = data->post_pwm_on_delay;
pb->pwm_off_delay = data->pwm_off_delay;

Privacy Policy